I'm having an issue with a vacuum leak at the intake manifold and I came across this statement: "Aftermarket headers have flanges that are thinner than the factory cast iron intake manifold leaving the thicker intake manifold loose causing a vacuum leak. The fix is to shim the clamping bridges so that both the intake manifold and the aftermarket header present a perfectly level surface for the clamping bridges" Has anyone here done this and have any further advice on doing this? Karl
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TR2/3/3A Anyone running an aftermarket header on their TR3?
- Thread starter karls59tr
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Karl
Some of the after market exhaust manifold plates are thin.
But the typical effect is that the exhaust is loose to the head as the football ( your type of football) shaped clamps tighten to the thicker inlet manifold first.
The typical fixes are to put a blob of weld on the exhaust manifold to raise the needed clamp area.
And or
Grind off the inlet side of the clamp enough to clamp both inlet and exhaust.
Some tack weld a small nut to the exhaust side on the clamp.
The first picture is an early set up I had with Su carbs and a 1970’s after market exhaust with thin plate to the head. With built up welds.
The other picture is my Weber set up with Phoenix big bore exhaust manifold and you can see they are close enough to equal thickness.
Some of the after market exhaust manifold plates are thin.
But the typical effect is that the exhaust is loose to the head as the football ( your type of football) shaped clamps tighten to the thicker inlet manifold first.
The typical fixes are to put a blob of weld on the exhaust manifold to raise the needed clamp area.
And or
Grind off the inlet side of the clamp enough to clamp both inlet and exhaust.
Some tack weld a small nut to the exhaust side on the clamp.
The first picture is an early set up I had with Su carbs and a 1970’s after market exhaust with thin plate to the head. With built up welds.
The other picture is my Weber set up with Phoenix big bore exhaust manifold and you can see they are close enough to equal thickness.
Thanks Hamish. I read this post after I sent my other reply on the other post.Now I see what needs to be done. I'm not even sure I used lock washers between the nut and the football clamps. I will look into that.